I figured out that I have to include (Add Reference) the downloaded *.dll files before using the class library.
* Not to mention that this is the ONLY library IN THE WORLD that requires an EXTRA step to make it ready for use, which UNLIKE OTHERS.
However, it seems that I still need QvxLib and QvxLib.Connector for use. I continue download them through NuGET, the QvxLib.Connector requires QvxLib to be installed before it could be installed. While ALL libraries, including QvxLib itself, can reference to the dependent libraries and automatically download all required libraries, such as NLog and Autofuc for QvxLib's example; QvxLib.Connect fails to reference to its sibling product, QvxLib.
There is only QvxLib.dll file in the two packages, i.e. QvxLib.1.0.4 and QvxLib.Connector.18.104.22.168. Whereas, the adding QvxLib.dll to the VS project did not make any change.
Still, the namespace `QvxView` is not correctly included / loaded as expected.
So, my question is: What is the actual correct way to include those library into a VS project?